CVE-2026-54282
Starlette is a lightweight ASGI framework/toolkit. Prior to 1.3.0, the HTTP request path is not validated before being used to reconstruct request.url. Because request.url is rebuilt by concatenating {scheme}://{host}{path} and re-parsing the result, a path that does not begin with / (for example @google.com) moves the authority boundary during re-parsing, so request.url.hostname and request.url.netloc become attacker-controlled.
Code that reads request.url.hostname (rather than the Host header or scope) can therefore be misled into trusting an attacker-supplied host. This vulnerability is fixed in 1.3.0.
- No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:NATT&CK techniques
1Techniques this CVE enables. Pills with a solid outline are high confidence - named directly in ATT&CK or Nuclei, or human-curated by CTID; the rest are inferred from the weakness type using MITRE's CVE Mapping Methodology and the CWE → CAPEC chain. Broad, generic-weakness guesses are filtered out. A small N× marks a technique that N independent sources agree on.
▤ Build a SIEM detection for these techniquesCAPEC attack patterns
4Attack patterns this CVE enables - the bridge from weakness to ATT&CK technique.